The Breast SPORE Pathology Core (PC) is dedicated to serving several needs of the Breast SPORE. (1) The PC provides a central facility for the collection and retrieval of tissues from benign and malignant breast lesions and other tissues (e.g. normal skin) that are required by SPORE investigators. (2) The PC maintains records of all specimens acquired. including a complete standardized pathologic diagnosis. (3) The PC distributes tissues to SPORE investigators according to priorities established by the Steering Committee of the Breast SPORE. (4) The PC serves as a central facility for performing and interpreting histopathological and immunohistochemical studies in tissue sections and cytology specimens (e.g.. estrogen and progesterone receptors. 5100. cytokeratins. etc.) required by SPORE investigators. (5) The PC develops. implements. and interprets histopathologic. immunohistochemical and other pathological studies in tissue sections and cytology specimens. using experimental markers developed by Breast SPORE investigators. (6) The PC relieves the investigators of the cost and burden of separately procuring specimens while at the same time protecting the privacy and uninterrupted clinical care of patients.